RFR 8025173 : HashMap.put() replacing an existing key can trigger a resize()

[Brent Christian]

Please review this change for 8025173, "HashMap.put() replacing an 
existing key can trigger a resize()."

A description of the problem can be found in the bug report:
http://bugs.sun.com/view_bug.do?bug_id=8025173

Thanks to Doug Lea for sending in the diff for HashMap.java.

Webrev is here:
http://cr.openjdk.java.net/~bchristi/8025173/webrev.00/

Results of an automated test run look okay.

Thanks,
-Brent